CA1130313A - ALKYL PERFLUORO-.omega.-FLUOROFORMYL ESTERS, THEIR PREPARATION AND MONOMERS THEREFROM - Google Patents

Abstract

ABSTRACT OF THE DISCLOSURE

Alkyl perfluoro-.omega.-fluoroformyl esters are provided which have the formula:

wherein R is alkyl of 1-6 carbon atoms, and n is 0-6 (preferably 0).
Compounds where n is 0 are prepared by contacting SO3 with a compound of the formula ROOC-CF2-CF-OR1. Compounds where n is 1-6 are prepared by contacting a compound where n is 0 with hexafluoropropylene oxide.
Also provided are polymerizable monomers having the formula:

Description

BACKGROUND OF THE INVENTION
Field of Invention This invention relates to fluorinated a-carboxylic-~-carbonyl fluorides, their preparation and the preparation of fluorinated vinyl ether monomers therefrom.
Prior Art Fluoromonomers containing carboxyl or carboxylic ester groups, such as described in U.S. Patent 3,546,186, issued December 8, 1970, have been difficult to prepare.
Such monomers are useful in preparing fluorohomopolymers or copolymers with tetrafluoroethylene. Thus, it would be advantageous to be able to prepare fluoromonomers easily.
Symmetrical difluoromalonic compounds of the formula CF2Q2 where O~ may be COOH, COOalkyl or COF are known (E.J.P. Fear et al., J. Appl. Chem., 5, 589-594 (1955); and J. Heicklen, J. Phys. Chem., 70, 618-627 (1966)).
Ryazanova et al., Zh. Vses. Khim. Obshchest, 1972, 17, No. 3, 347-8, describe compounds of the formula ROOC(CF2)nCOF where n is 3, 4 or 6.
Fluoromonomers having the general structure A-Y-CF2CF2O~CF-CF2OtpCF=CF2 wherein Y is -CnFmHl, where n, m, 1 are zero or positive numbers which satisfy the requirements of a difunctional fluorinated hydrocarbon residue, and A is a functional group including -COOR, -SO2F
and -COF, are disclosed in German Application 2,504,622, published August 7, 1975.
Fluoromonomers of the above general structure in which A also includes -CN are disclosed in German Application

2,659,581, published July 13, 1977.

- 2 - ~r~

3i3 No method of preparing the above monomers is provided in either of the above applications. The first disclosures of a preparatlve method of which we are aware are contained in German Application 2,635,312, published February 17, 1977, Japanese Application J5-2,003,017, Serial No. JA 079326, published January 11, 1977, and Japanese Application J5 2,105,118, Serial No. JA 020144, published September 3, 1977. Taken together, these applications describe the reaction of perfluoroalkyl diiodides I(CF2)nI, where n = 3-5, with fuming sulfuric acid to form a lactone;
reaction of said lactone with HFPO to form a ~-~ diacylfluo-ride; and conversion of the diacylfluoride to esters of the formula R2C RF-tCF2O-CFl-nCF2OCF=CF2 wherein RF is perfluorinated alkyl of 1-10 carbon atoms and n = 1-5, preferably 1-2.
Fluoromonomers having the general structure CF2=CFO(CF2)n-X, where X includes -CO2R and -CN, R = H or alkyl of 1-10 carbon atoms, and n = 2-12, preferably 2-4, are disclosed in U.S. Patent 3,546,156 issued December 8, 1970.
Such monomers are useful in preparing fluorohomopolymers or copolymers with tetrafluoroethylene, but have been difficult to make from symmetrical compounds such as FOC-(CF2)n-COF.
Fluoromonomers having the formula FSO2-CF2cF2OtcF-cF2ot-pcF=cF2 are disclosed in U.S. Patent

3,282,875, issued November 1, 1966. Preparation of -these monomers by reaction of FSO2-CF2-COF with hexafluoropropylene oxide (HFPO) is disclosed in U.S. Patent 3,301,893, issued January 31, 1967.

113~3 Fluoromonomers of the ormula CF3-CFcF2O-tcFCF2o~ncF=cF2 containing secondary -CN groups are disclosed in U.S. Patent 3,852,326, issued December 3, 1974. Such monomers are prepared by reacting CF3CF-COF with HFPO.
CN
Conversion of fluoromonomers of formula FSO2-CF2CF2O-tCF-CF2o~nCF=CF2 to carboxylated monomers of formula HOOC-CF20-~CF-CF20~tnCF=CF2 is disclosed in : CF3 Japanese Application J5 2053-814, Serial No. JA 129691, published April 30, 1977.
Fluoropolymers having the formula - ( CF2CF2 ~ CF2CF-~n CF-CF
~1-3 A

where A is an acid group which includes -COOH and -SO3H, are disclosed in U.S. Patents 3,853,720 and 3,~53,721, issued December 10, 1974. These patents do not disclose a method of preparing the fluorinated vinyl ether monomers.

SUMMARY OF THE INVENTION
Accord~ng to the Present invention there is provided a compound of the formula:

CF2~ CF2_o_CF ~ COF

wherein R is alkyl of 1-6 carbon atoms, and rl is o-6.
Also provided is a process for preparin~ ROOC-CF2-COF
comprising: contacting SO3 with a c~mpound of the formula wherein R and Rl, alike or different, are alkyl of 1-6 carbon atoms.
Further provided is a proces~ for preparing a compound of the ~ormula COOR ~ 3 CF2 ~ CF2-0-CF ~ COF
: wherein R is alkyl of 1-6 carbon atoms, and m is 1-6, comprising: contacting a compound of the formula ROOC-CF2-COF
where R is as defined above with hexafluoropropylene oxide.
Further provided are polymerizable monomers of the formula Y CF3 CF2CF20 ~ CF-CF20 ~ CF=C~2 wherein Y is -COOR, -COOH, -COOM or -CN, R and M are defined as above, and p is 1-5, and processes for preparing such monomers -from compounds o~ the formula COOR CF3 CF2 ~ CF20CF ~ COF

DETAILED DESCRIPTION OF THE INVENTION
- The compounds of the invention are fluorine-contain-ing a-carboxylic-~-carbonyl fluorides of the formula COOR / CF3 \
~F2 t CF2-O-CF ~ COF
` 30 113~3:13 in which R is alkyl of 1-6 carbon atoms, particularly methyl or ethyl and n is o-6, pre~erably 0.. The compound H3COOC-CF2-C0F is most preferred.
The compounds of the invention where n is 0 are prepared by reacting lower alkyl ~-alkoxytetrafluoropropionates ~iley U.S. 2,~88,537) with sulfur trioxide to obtain the correspondin~ carboalkoxydifluoroacetyl fluorides according to the equatlon C~OR COOR
CF~-CF2-ORl SOo > CF2-COF
I~ III
The compounds of formula III are then reacted with hexafluoropropylene oxide to obtain the a~c~rboxylic~ carbonyl ~luorides of formula Y 1 wh~ch m ~ 1-6, according to the equation CF2-COF ~ CF2-CF-CFS -~ CFz ~ CF2-O-CF ~ COF
~ III IV V
; ~he reaction o~ compounds of formula II with sulfur trioxide is exothermic and provision should be made ~or dissipating the heat of reaction. One method ls to add the alkoxyester compound of formula II in small portions to the S03 with cooling by reflux condenser or external cooling means. Alternatively, the SO3 can be added in small por~ions to the alkoxyester, but the ormer procedure is pre~erred. The reaction can also be carried out on a continuous basis by slowly feeding the separate reactants into a cooled reaction zone from which product is continuously withdrawn. Sulfur trioxide can be 3 used either in monomeric form or polymeric form. The ~3~33:~3 reaction is preferably carried out neat. However, it can be operated also in the presence of diluents whlch are relatlvely lnert to S03 or which couple with S03, e.g., dioxane, chloroform, carbon tetrachloride, ~luorocarbon liquids and the like. Temperatures at which the reaction is operable range from about -30C to about 250C and temperatures from about 0-100C are preferred.
Pressure is n~t a critical ~ariable and pressure both below and above atmospheric pressure can be employed. The molecular proportions in w.hich S03 and the compounds of formula II can be brought together to carry out this reaction can be varied widely such as ~rom about 1:20 to 20:1, preferably about 2 to 1.
The reaction o~ a compound of formula III with hexafluoropropylene oxide is preferably carried out in ~he presence of fluoride ion as a catalyst. This is readily accomplished by using a suitable fluoride, e.g., an alkali metal fluoride such as cesium fluoride, potassium ~luoride; sil~er fluoride; ammonium fluoride; a tetra-alkylammonium fluoride (alkyl Or 1-4 carbons) such as tetra-methylammonium fluoride, te~raethylammonium fluoride, and tetrabutylammonium fluoride, and sulfonium fluorldes such as benzene sulfonium fluoride. The fluoride catalyst is usually used in conjunction with an inert liquid diluent ~preferably - an organic liquid) in which the selected fluoride is at least 0.001% soluble. The fluorlde catalyst may be used in amounts rxom about 0.001 to about 1.0 molar equivalent per mole of the compound of formula III. Suitable diluents include ethylene glycol dimethyl ether, dieth~lene glycol dimethyl ether, tetraethylene glycol dimethyl ether, and aprotic , ~13~ 3 solvents such as acetonitrile. The reaction is somewhat exothermic and pr~vision for dissipation of the heat of reaction should be madeO Temperatures employed can range from about -50C to about 200C with temperatures in the range of about -10 to about 80C being preferred. Pressure i~ not a critical ~ariable and pressures both below and above atmospheric pressure are operable. Hexafluoropropylene oxlde is a gas over much of the operable temperature range and pressures close to atmospheric pressure are preferred.
Operable molar proportions o~ hexafluoropropylene oxide to the compounds o~ ~ormula III can vary rrom about 1:20 to about 20:1, preferably abou~ 1 to 1.
As illustrated in the examples, more than one mol o~ hexafluoropropylene oxlde c~n react with a compound of ~ormula III to yield compounds of formula V in which m is greater than one. To obtain products with higher ~alues o~ m~ higher molecular proportions o~ hexa~luoropropylene oxide are employed and higher pressures and lower tempera-tures are selected. To o4tain products with lower values of m (e.g. 1 or 2) higher molecular proportions of thecompound of formula III are employed and lower pressures and higher temperatures are selected.
Each of the compounds Or formula I is a reactive organic compound which is at once a carboxylic ester and an acid fluoride. Such fluorinated compounds are rare, and understandably so because the known processes for synthesizing dl~unctional carboxylic compounds readily yield dicarboxylic esters às well as diacid fluorides but teach àlmost nothing about how to obtain compounds with both a carboxylic ester 3 group and a carbonyl fluoride group in the same molecule.

.

In carrying out reactions with compounds of formula I care must be taken to prevent their ready conversion to the more ordinary corresponding dicarboxylic esters or dicarbonyl fluorides.

Compounds of formula I are useful as intermediates ln the preparatlon o~ new ~luorine~substituted polymerizable ole~inic compounds containing carboxylic acid, ester or nitrite groups. As shown in the examples, the compounds of ~ormula I

in which n = 0 can be reacted with hexaf.luoropropylene oxide in the presence of fluoride ion catalyst to prepare the compounds of formula I in which n is 1 to 6, e.g., the compounds o~ formula V. In turn the compounds of formula V can be pyrolyzed over a solid basic salt such as sodium phosphate, sodium carbonate or potassium carbonate at moderate tempera-tures to obtain the corresponding polymerizable monomers of formula Vl according to the equation ~Example 7) CF2 ~ cF2ocF ~mcoF ~ CF2CF20~ CF-CF2-O ~pCF-CF2 ~20 V V~ (p is 1 to 5) .
~ As illustrated in the examples, the monomers of ;~ ~ormula VI can be homopolymerized to heavy oils suitable as lubricants and can be copolymerized with one or more comonomers such as, for example, tetra~luoroethylene or chlorotri~luoroethylene, to yield tough, solid polymers which are thermoplastic and capable o~ being hot pressed or rolled into sheets and films for wrapplng usesg as protective layers where exceptional chemical stability is required and as ion exchange membranes in electrolysis cells.

~13~3 For polymer uses re~uiring ion-exchange capability, such as electrolysis cell membranes, monomers of formula VI
ma~ also be polymerized in a ~orm in which the terminal functional group is -COOM or -COOH. The metal salts (-COOM) are produced from the esters (~COOR) by hydrolysis with alkali metal hydroxldes, ammonium hydroxi.de or quaternary ammonium hydroxide. The free acids (-COOH) are readily produced by acid-catalyzed hydrolysis of the diesters in cold water.
Alternatively, monomers of ~ormula VI can be converted as illustrated in Example 8 to polymerizable monomers containing primary -CN groups:
COOR CF3 CN C~3 CFeCF20 t-CF-CF2O ~pCF=CF2 ~ ~H3~ CF2CF20 ~dF-CF20~pCF=CFz VI - VII
Monomers o~ formula VII can also be homopolymerized or3 preferably, copolymerized with one or more comonomers ~: such as, for example, tetrafluoroethylene, chlorotri~luoro-ethylene or perfluoromethylvinylether, to yield tough, solid polymers in the same manner as formula VI monomers (Utility Examples A-D). Formula VII monomers, by virtue of their primary -CN groups, are especially useful for incorporating cure sites into elastomeric copolymer compositions.

The polymerizable monomers of this invention contain a tetrafluoroethylene segment -CF2CF~- between the : terminal -COOR or -CN groups a.nd the first ether oxygen, -e.g., carbons (1) and (2) in the structure CF2CF20 ~ CF-CF20 tCF=CF2 (1)(2) P

3~3 ~he art-provides a means of preparing structures of the formula CF2C:?20~ CF-CF20~ CF=CF2 VIII
However, it is not known how to convert formula VIII struc-tures to the corresponding carboxylated compounds because one -CF2- is necessarily consumed in such conversions; thus CF2CF20 ~ CF-CF20 ~; CF=CF2 ~ >
VIII

; CF20 ~ CF-CF20 ~ CF=CF2 IX
While monomers of formula IX are useful they are distinctly different a.nd demonstrably inferior to the monomers of this invention in the properties they impart to copolymers prepa.red from them. For example~ experiments su~marized in Tables 1 and 2 show that copolymers 'O o~ monomer VI (R-~) with tetrafluoroethylene are superior to similar copolymers o~ monomer IX (R=H) in tensile properties a.nd in retention of these properties on e~posure -~ to heat and high concentrations of alkali~.conditions found in chlor-alkali electrolysis cells ~here carboxyl functional ~luorovinylether copolymers are useful as membranes.

~ 31 3 Table 1 Tensile Properties After Aging in 30~ NaOH a.t 90C
Days Tensile Strength Elongation 55~ A~ed PSi (~) 61 3200 ~8 TFE/IX O 37oa 120 <lO --' ~
Table 2 . .
Days to Onset o~ Film Brittleness in Alkaline Environment Temperature CopolymerCo~olymer Solution(C) _ TFE/VI TFE/IX
25~ XOH l110 >0.1 <0.1 25% D~IS05 ~0~ NaOH115 >lO 3-7 - 30% NaOH 90 120 20 ~Defined as rupture when film i~ bent 180.
Copolymers prepared ~rom formula VI and ~II monomers may be represented by the repeating unit - CF-CF2- ~-[~X -C
I

C~
. . ~ 2 ~p O
CF -CF -Y

:~3~)313 in Which Y ls -COOR, -COOH, -~OOM, or -CN, where R and M
are defined as above, p is 1 to 5, q is O to 1000, the X's may all be fluorine or two fluorine and one chlorine, and Z is -F, -RF or -OR~ where RF is perfluoroalkyl of 1-6 carbon atoms, preferably 1-2 carbon atoms. The preferred copolymers are prepared from two or more monomers and have average compositions represented by the above formula where p is 1 or 2 and q is 1 to 200. Values o~ q from 1 to 9 are preferred for carboxylated copolymers used as electrolysis cell membranes; q of 20 to 200 is preferable in nitrile-functional elastomers.
In the examples which follow parts are by weight unless otherwise speci~ied.
Example 1 fOOCH3 `,~, ' CF2-COF
;~ Sulfur trioxide (40 ml) was added to a 3-neck flask attached to a still and fitted with a dropping funnel and thermometer. Crude CH30CF2CF2COOCH3 (100 g) was added dropwise from the ~unnel to the magnetically stirred sulfur ~ trioxide at a rate to maintain a gentle reflux due to the ; exothermic reaction. When addition was complete, the mixture was distilled at atmospheric pressure. Product distilling - at 82-86C was shown by gas chromatographic analysis to . .
contain about 69.5 ~ of H3COOC-CF2-COF (85%) and the remainder mostly CH30S02F. This mixture was passed over sodium fluoride pellets at about 400C/4 mm, converting the CH30S02F
to CH3~ and NaOS02F. Pure H3COOC-CF2-COF was then isolated by distillation.

)313 Example ?

CFz-COF ~ CF2-CF-CF3 CsF ~ CF2-cF2-o-cF-coF
\o In a 250 ml glass flask fltted with a dry ice condenser and ports for add~tlon of gases, liqulds and solids,was placed 20 ml tetraglyme (tetr~ethyleneglycol dimethyl ether), 6.0 g CsF
~nd 26.3 g ~rude HacooccF2coF (containlng 3~g CH30SO2F).
Wlth the mixture kept below 15C, 29.2 g of hexafluoro-: propylene oxide (HFPO) was slowly added. Upon completion of the reaction~excess H3COOCCF2COF and HFPO
were remo~ed under YaeUum at 40C. The residue wss dlstilled ~n~ crude H3COOC-CF2-CFz-O-CF(CF3)-COF
d~st~lled at 75-95 C/400 mm. Its structure was con~irmed by:
IR (llq): 1900, 1820~ .1330, 1250, 1140, 1035 cm PMR (CCl~): 4.04 ppm (slnglet~
FMR ~C~14): ~ 21.6 (multiplet, lF), -82.4 (broad mult., ..~
4F), -86~3 (mult., lF), ~llg.8 (mult.~ ~F), ~20 ~130 ppm (mult., lF3 .

~3~313 xample ~i A 150 ml Carius tube was loaded with a mixture of 0.5 g each of CsF and KF (vacuum dried at 400C)) 3 ml tetraglyme, 34.5 g H3COOC-CF2-COF and 60 g HFP0.
The tube was sealed and rotated overnight at room temperature. Dis~illation of the reaction mixture ylelded 15 g H3COOC-CF2-CF2-0-CF~CF3)-COF, b.p. 65~/100 mm.

; Anal. Calcd. ~or C7H3F~O~: C, 26.10; H, 0.94;
F, 5~.09 Found: C, 25.87; H, o.8g;
F) 53.34 .
' ~xam~le 4 CF2COF I C 2-~CF-CF3 ~ CF2 ~ CFz-O-CF ~nCOF
. O

Powdered cesium fluoride (15 g) was placed in a 500 ml 4-necked ~lask, which was then plugged ~20 except for a conne~tion to a manifold attached to a - vacuum pump and open-end manometer. ~Pcuum was ~pplied to the flask whlle it was heated with a Meeker burner to thoroughly dry the cesium fluoride.
After the ~lask had coo-led~ dry nitrogen was admitted snd then a large magnet1c stirrer. The flask was - fitted w~th a thermometer, reevacuated, filled wlth nltrogen and 20 ml of tetraglyme and 63 g (0.4 m) of HaCOOCCF2COF added. The flask was then cooled to -10C, evacuated and filled to 600 mm pressure with hexafluoro-propene epoxide (HFP0) three times. Stirring was started and the pressure of HFP0 was maintained autom~t~cally ~13~313 at 600 mm by a vacuum regulator. The HFP0 was absorbed ~teadily in an exothermic reaction and cooling was ~ecessary to keep the temperature between 0 and -lOaC.
The reaction was stopped after 140 g (0.84 m) o~ HFP0 had been absorbed.
The low layer (190 g) was distilled. The products obtained are tabulated below. The ratio o~
products formed can be varied by the temperature of reaction and mainly by the amount o~ HFP0 used.

; PRODUCTS
` 10 Emplrl^ A~IA~YSES
pO~DU~a b.p. wt. cal ~C
n ~ _ C~ e~ ~or~ula Calcd. Pd . Ca'~~d. -~d. Calcd ~A ~
6shoo 11.8 C7H~F90~ 26.10 25.87 0.9~ 0.89 53.09 53.34 210~100 14.9 C~OH3F~Os 24.61 24.65 0.62 0.74 58.39 58.49 57;0.3 31.3 C~3~Fa~0~ 23.~7 24.07 o.46 0.61 60.99 60.72 9~/0.2 42.5 Cl~H~F~07 23.43 23.78 0.37 0.4a 62.55 62.40 585/o.2 24.8 CI~H~F~oe 23.~4 23.51 0.31 0.52 63.58 63.29 6107~0;5 5.7 ~ . ' ~ , .
The procedure of Example 4 was repeated except that 182 g (1.17 m) o~ H3COOCCF2COF wa6 used, no cooling was used ~run at 55C) and the add~tion o~ HFP0 was stopped after 190 g had been a~sorbed.
In the d~stillatio~ 100 g of H3CO~CCF2COF was reco~ered and the products obtained were 87.5 g (0.27 m, 23~) o~ the product where n = 1, 40 g (o~o8 m~ 7~) o~
the product where n = 2 and 10 g (0.015 m, 1.
o~ the product where n = 3.

Ex~mple 6 COOc~3 ~0 0C~3 IC~?3 ~FzCFzOCF(CF3)COF ~ CF2-CF-CF3 ~ CF2 ~ CF2-O-CF ~nCOF

3o ~ 313 Using the apparatus and general procedure Or Example 4,the reaction of 15 g o~ CsF, 20 ml tetraglyme, 234 g of H3COOCCF2CF20CF(CF3)COF and ~3 g HFP0 was carried out at 68C. Distillation yielded 38 g (o.o8 m, ll~) o~ the above product where n = 2 and 6 g (0.01 m, l~) of the product where n = ~.
Example 7 - COOCH3 CF3 ~F3 COOCH9 CF3 .^ I I I Na3PD~
CFzCFzOCFCF20CFCOF ~ CF2::F20CFCF20CF=CF~

. .
Into the top of a ~ertically mounted quartz tube l inch in diameter and 12 lnches long containing 90 cc of fine granules o~ sodium phosphate (predr~ed at 40oC) stirred by a motor dri~en stainless steel : screw in the center, the granules heated to 235-240C
; by an external split-type ~urnace, was passed 6.4 g o~ H3COOCCF2CF20CF(CF3)CF20CF(CF3)COF along with a slow current of nitrogen over a period of 9 minutes.
: Off-vapors from the bottom of the tube were condensed and collected in a Dry Ice-acetone cooled trap. The quid product was distllled to obtain 3.7 g (67%) o~
~ethyl 3-~2-(trifluoroethenoxy)-l-(trifluoromethyl)-~rlfluoroethoxy~tetrafluoropropionate7 b.p. 98C/llO mm.
: AnPl. C~lcd. ~or C~H9Fl30~: C, ?5-6l~ H, 0~72;
~, 58.51 ~ound: C, 25.47; H, 0.81;
~, 59.87.

~1~3~313 Example 8 COOCH3 CF3 lONH2 fF3 CF2CF2OCFCF2OCF=CF2 + NH3 3 CF2CF20CFCF2OCF=CF2 ~ CH30H

IONH2 Tri~luoroacetic CF2CF2OCFCF20CF=CF anhvdride 2 pyridine CN CF
CF2CF20CFCF20CFaCF2 + H20 8 g (0.47 mol) of ammonia was added slowly with stirring from a weighed cylinder to 200 g (0.47 mol) of methyl - 3-[2-(trifluoroethenoxy)-1-(triflùoromethyl)trifluoroethoxy]tetra-fluoropropionate (Example 7) and 150 cc~ of ether contained in a flask cooled in a Dry Ice acetone bath (ca. -80C) and evacuated. The amide so formed was extracted at room temperature with 1,1,2-trichlorotrifluoroethane, washed with water and then distilled; yield 17 g. of clear liquid;
b.p. 90C at lmm. Hg.
The above amide was dehydrated to the nitrile by a method similar to that described by Campagna et al. Tetra-hedron Letters No. 21, 1813 (1977). 170 g (0.42 mol) of amide was dissolved in 150 cc of tetrahydrofuran at -10C, and 80 cc (1.0 mol) of pyridine and 70 cc (0.50 mol) of trifluoroacetic - anhydride were added consecutively, with stirring, dropwise, maintain-ing temperature at -10 to 0C. The mixture was allowed to warm to Z5C, ice water was added, and the product layer was separated with the aid o~ a small quantity o~ 1,1,2-tri-chlorotrifluoroethane. The product was washed ~ive times with water, then distilled. Re-distillation over P2O5 is sometimes necessary to remove traces Or water. Yield 135.3 g; b.p.
95-102C.

113~313 . UTILITY EXAMPLE A
(1) r r I ~
. . CF2 ;; FC-CF9 .~ ~ O
CF2CF2COO~I9 A ~lass tube containing 2 g of methyl 3-[2 (trifluoroethenoxy)-l-(tri~luoromethyl)tri-~luoroethoxy~tetrafluoropropionate and 0.01 ml - of a 6~ solution of perfluoropropionyl peroxide ln 1,1,2-trichlorotrifluoroethane was sealed under ~- vacuum and~ rotated overnight at ro~m temperature.
RemD~al of unreacted monomer under vacuum le~t 0~5 g of oily homopolymer having a repeating unit of the above formula.

(2) ~ CF-cF2 ~ CFZ-cF

CFz o . . . .
~ glass tube contalning 6 g o~ methyl 3-l2-(tri~luoroethenoxy~ (t~ u~ro~ethyl)trlfluor ethoxy]tetrafluoropropionate7 1 g ~etrafluoroethylene and 0.01 ml of a 6~ solution of perfluoroproplonyl peroxide in l~lJ2-trichlorotrifluoroethane ~as sealed under vacuum at llquid nitrogen temperature and then rotated at room temperature overnight 113~313 The mlxture became ~ery viscous. RemR~ning tetrafluoroethylene was bled o~f and an addltional .
5 g of tetrafluoroethylene and 0.01 ml of the perfluoropropionyl peroxide solution was sealed into the tubeO The tube was rotated ~or 5 hours at room temperature and then opened. Removal o~
Yolatiles at 100C under ~acuum left o.6 g of elastomeric copolymer of the above repeating unit where q is greater than 1.

(3) ~ CF-CFa ~ CF8-CF~

CF~
. FCCF9 . CF2-CF2-COO~
A 20 ml Carius tube containing 6~8 g (O.OlÇ m) of methyl 3-~2-(trifluoroethenoxy)~
(~rifluoromethyl~trifluoroethoxy ~etra~luoropropionate, 1.7 g (0.017 m) of tetrafluoroethylene, 2 ml of lJl,2-trichloro~rifluoroethane and 0.01 ml o~ a 6 solution of perfluoropropionyl peroxide ln 1,1,~-trichlorotrifluoroethane was se~led at liquid nitrogen temperature, rotated at room temperature overnight and then opened. The solid produ t was separated by filtration and washed with ether to obtain 1.7 g o~ elastomeric copolymer.
The copolymer was pressed at 250C under 500 p3i to yield a 3 mil film which showed strong infrared absorption for e~ter Garbonyl at 5.5 ~. Th1s fil~
. was heated for 3 hours at 100C in a solution of 15 g ~OH ln 35 g water and 35 g dimethylsulfoxide 31~

(DMSO). Infrared examinatlon of the resulting ~ilm , .
showed the ester carbonyl band had been replaced by carboxylic acid absorption (broad at 2.8 ~ for -OH and at 5.95 ~ for C-O). This con~irmed that a copolymer of the above repeating unit where q is greater than l was obtained.

(4) COOCH3 7F3 COOCH3 CF3 CF2(CF20CF)3COF Na~P04 ~ CF2CF20(CFCF20)2C 2 ;~ Using the apparatus and general procedure of Example A(l) above,22 g of H3COOCCF2[CF20CF(CF3)]3COF was passed slowly with nitrogen over Na3P04 at 235-240C.
~` Distilla~io~ of the collected product yielded 12 g (61%) o~ methyl 3-[2-(2-~tri~luoroethenoxy~-1-ttri~luoromethyl]trifluoroethoxy)~l-(trifluoromethyl)-trifluoroethoxy]te~rafluoropropionate, b.p. 71C/5.5 mm.
Anal. Calcd. for C12H3F1905: C, 24.50; H, 0.51;
~, 61.38 Found: C, 24.28; H, o.68;
~, 61.44 UTILITY EXAMPLE B
20 (l~ fOOCH3 CF3 COOH C~3 I l~NaOH > I I -2)HCl 2 .
In a separatory funnel 15 g o~ crude COOCCF2cF20cF(cF3)cF20cF=cF2 wa shaken with 25 ml o~ 10~ ~queous NaOH at room temperature. The ~q~eous layer was separated and acldifled with cold c~ncentrated HCl- The lower layer which separated ~8 dlstllled from a little P2OS to obtain 10.7 g 3~J/

~13Ci 3~3 of 3-t2-(trifluoroethenoxy)-1-(tri~luoromethyl)trl-rluoroethoxy~tetrafluoropropionic acid, b.p.
53C/0.25 mm, nD = 1.3078.
Anal. Calcd. for C~HFl30~: C, 23.54; H, 0.25; F, 60.53;.
Neut. Eq., 408.
Found: C~ 23.80; H, 0.52; F, 61.71;
~eut. Eq., 407.7.

(2~ ~ CF-CF2 ~ ~ CF2-CF

A glass tube containing 8.8 g of 3-[2-(tri-fluoroethenoxy)-l-(trl~luoromethyl)trifluorO~
ethoxy]tetra~luoropropionic acid, 2.2 g tetrafluoroe~hylene, 13 ml 1J1,2-trichlorotri-; ~uor~ethane and 0.01 ml of a 6~ solution of per-fluoropropio"yl peroxide ln 1,1,2-trlehlorotri-~luoroethane was sealed and rotated at room temperature for 60 hours. ~ases were bled off ~n~ 3 g tetr~fluoroethylene and 0.01 ml of a 6~ solution of per~luoropropionyl peroxide in 1,1,2-trichloro-~rl~luoroethane were added. The tube was sealed, ratAted overni~ht at room temperature and then opened. Flltr~tion and w~shing in ether yielded z,3 g Or copolymer o~ the repeatin~ unit indicated above where Q is greater than 1. A pressed ~ilm showed strong lnrrared absorption for -COOH.

3(:~313 UTILITY EXAMPLE C

3F_cF2~Crz~CF

ij CF

` ¦ .
O

~F2CF2cOoH

Using the general procedure of Example A(3), six 20 ml Carius tubes were each charged with 0.01 ml of a 6%
solution of perfluoropropionyl peroxide in 1,1,2-trichloro-trifluaroethane and the respective quantities of methyl 3-~2-(trifluoroethenoxy)-1-(trifluoromethyl)tri~luoroethoxy]-tetrafluoropropionate (vinyl ether), tetrafluoroethylene (TFE) and 1~1~2-trichlorotrifIuoroethane (svlvent) indicated in the table below. The tubes were sealed at 11quid nitrog~n temperature, rotated at room temperature overnigh~, cooled and opened. The respec~ive amounts of copolymer were recovered by filtration, washed with ether and dried.

Vinyl T~ESolven~ Copolymer Tube Ether (~) ~g)(ml) 30.4 7.2 ~ 2.45 19.5 4.6 4 2.31 : C 1~ 5 5 3.01 ~ 19 5 ~ 3.55 .E 12.9 3 12 2.9 F 12.8 3 8 ~8 ~13~313 The six copolymer products were combined and a film was pressed at 360C/20,000 psi. After hydrolysis ln KOH-H2O-DMS0 as ln Example A(4) the copolymer was shown to have a neutral equivalent of 1500, confirming that the copolymer had the average composition represented by the formula above.

. .
(2) ~ F-CF2 ~ CF~-CF

~CF3 - d A glass tube containing 8.8 g of 3-~2-(tri-fluoroethenoxy)-1-(trifluoromethyl)trifluoroethoxy]tetra-fluoropropionic acid, 2.2 g tetrafluoroethylene, 13 ml ~ 2-trichlorotrifluoroethane and 0.01 ml of a 6%
solution of perfluoropropionyl pexoxide in 1~1,2-trichloro-trifluoroethane was sealed and rotated at room temperature ror 60 hours. Gases were bled off and 3 g tetrafluoroethylene and 0.01 ml o~ a 6% solution of perfluoropropionyl peroxidein 1,1,2-trichlorotrifluoroethane were added. The ~ube was sealed, rotated oYernight at room temperature and then opened.
Filtration and washing in ether yielded 2.3 g of copolymer o~ the repeating unit indicated above where q is greater than 1. A
pressed film showed strong infrared absorption for -~OOH.
UTILITY EXAMPLE D
(1) Titration of 12.671 g (0.031 m) of 3-~2-(tri-rluoroethenoxy)-l-(tri~luoromethyl)trifluoroethoxy]tetra-3o --21~--3~3 :, fluoropropionic acld to a neutral end point (phenolphthalein lndicator) with 15.54 ml of 0.2N sodium hydroxide lndicated a neutral equivalent of 407.69 (Calcd. 408). An excess o~
1 ml of 0.2N NaOH was added and the solution frozen in a 50 ml Carius tube. Then a solutlon of 0.25 g ammonium persulfate in 10 ml water~ a solution of 0.2 g Na2S2O3 5H2O in 10 ml water and 3.1 g tetr~fluoroethylene were added separately with freezing before sealing the tube~ The tube was rotated o~ernight at room temperature to obtain a clear solution and a lit~le solid polymer. The solution was filtered and acidified to give a gel which was mostly soluble in ether. Removal of ether and drying at 100C
-under vacuum gave 3.2 g of copolymer from which a film was pressed at 100~C/10,000 psi. The copolymer absor~ed ; strongl~ in the infrared for -COOH (broad 3 ~ and 5.7 ~).

(2) ~ CF-CF2 (CF2 CF2)1 ~
fF2 FfCF3 .

CF2CF2CNa Using the general procedure of Example D(l) a 200 ml Carius tube containing 6 g (0.015 m) o~
3-~2-(trifluoroethenoxy)-1-(trl~luoromethyl)trifluoro-ethoxy]tetrafluoropropion~c acid neutralized with a slight excess of 0.2N sodium hydroxide, 0.25 g ammonium persulfate in 10 ml water, 0.02 g Na2S203-5H2O in 10 ml water and 10 g tetra~luoroethylene was rotated overni~ht 3o - ~3~ i3 at room temperature and then cooled and opened. A gel-like polymer (sodium salt) was collected by filtration and vacuum dried at 100C to gi~e 6.5 g of copolymer of the average composition indicated by the above repeating unit tneutral equivalent by titration 1976). The filtrate was acidi~ied to give an acid copolymer which was collected by ~iltration and vacuum dr~ed at 100C (wt. 5.8 g).

~ 10

Claims (9)

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:

1. A compound of the formula:

wherein R is alkyl of 1-6 carbon atoms, and n is 0-6.

2. The compound of Claim 1 wherein n is 0.

3. The compound of Claim 1 wherein R is methyl or ethyl.

4. The compound of Claim 2 wherein R is methyl or ethyl.

5. A process for preparing ROOC-CF2-COF comprising:
contacting S03 with a compound of the formula ROOC-CF2-CF2-OR1 wherein R and R1, alike or different, are alkyl of 1-6 carbon atoms.

6. The process of Claim 5 wherein R is methyl or ethyl.

7. A process for preparing a compound of the formula wherein R is alkyl of 1-6 carbon atoms, and m is 1-6, comprising: contacting a compound of the formula ROOC-CF2-COF
where R is as defined above with hexafluoropropylene oxide.

8. The process of Claim 7 wherein the contacting is carried out in the presence of fluoride ion as catalyst.

9. The process of Claim 8 wherein the fluoride ion is from a fluoride compound selected from the group consisting of alkali metal fluoride, ammonium fluoride and tetraalkyl-ammonium fluoride where the alkyl is from 1-4 carbon atoms, said fluoride compound being contained in an inert liquid diluent in which the fluoride compound is partly soluble.